The present invention relates generally to a digital video tape recording/reproducing method, and more particularly, to a method for recording/reproducing video data for trick play in a digital video tape recording/reproducing apparatus which records/reproduces an advanced television signal.
Recently, a commercial-purpose digital video cassette recorder has been developed, which can record/reproduce the advanced television (ATV) signal on/from digital video tape for a standard-definition VCR. The bit stream of a standard-definition VCR is 24.9 megabits per second, whereas the bit stream of the ATV signal is 19.3 megabits per second. This leaves an area for recording 5.6 megabits per second on the video tape. There has been much investigation as to how best to record trick play data on the remaining video sectors and an unused audio sector in order to facilitate trick play reproduction of the ATV signal at various speeds, as well as to accomodate various types of scanners, and in order to improve picture quality and solve noise problems. The present invention, which resulted from one such investigation, encompasses a technique for recording trick play data in such a manner as to enable the realization of a desirable digital video tape player for the home.
A fundamental problem in digital video cassette recorder development lies in the recording format for special reproduction modes (trick play operation). The format must be structured such that two requirements--better picture quality and cost reduction--are satisfied.
One solution to the above problems is to allocate the trick play data throughout the entire scanning area, portions of which respectively correspond to each of a given set of playing speeds. This method can provide better picture quality for a reproduced image during trick play operation, but presents a drawback in that the correspondingly allocated area must be scanned, so that a servo control operation must be carried out with a high degree of precision, thereby increasing the cost and complexity of the VCR, and degrading the reliability thereof.
An alternative solution is to repetitively record the trick play data normally recorded on a pair of tracks onto a number of tracks which correspond to twice the maximum-fold playback speed. In accordance with this method, scanning is performed in the repetitively recorded area only, so that the servo control need not be so precise, which somewhat reduces cost and complexity. However, the repetitive recording may consume a large recording area, and the duration for displaying each still image is longer during low-speed playback than it is during high-speed playback. This lengthy interval between updated images tends to make the viewer impatient, and picture quality suffers as well.